What: "Researchers are familiar with nucleic acids, RNA, proteins, and maybe even carbohydrates, but usually not with lipids," says Zheng Cui, a biochemist at Wake Forest University School of Medicine. "Lipids are probably the most ignored type of molecules by the entire field of biological sciences, and yet they play a key role in many of the functions of the body." For example, lipids function as both energy stores and signaling molecules, and they literally define cells, separating the intracellular from the extracellular components with an impermeable bilayer."